Four-lined plant bug nymphs (Poecilocapsus lineatus) have been found on many
different kinds of plants including wild hydrangea (Hydrangea arborescens). This
insect feeds on 250 species, including many kinds of perennials, vegetables, and
shrubs such as bluebeard, forsythia, and sumac. Feeding injury is frequently
mistaken for leaf spots. Four-lined plant bugs have a piercing, sucking
mouthpart which they use to break plant cells and then flush the feeding wound
with digestive juices.

Damage appears as dark leaf spots which
subsequently turn translucent. The damage they do is more serious on herbaceous
plants than on woodies. Sometimes by the time the damage is noticed, the insect
isn’t there anymore. Both nymphs and adults feed on leaves, creating the spots.
Nymphs are bright yellow to red with rows of black spots on the abdomen. The
adult stage is ¼” to 1/3” long and has four longitudinal black lines on its
yellow or green back, thus the name.